Telecommunications systems, cable television systems and data communication networks use networks to rapidly convey large amounts of information between remote points. One type of network used to convey such information is an optical network. In an optical network, information is conveyed in the form of optical signals through optical fibers. Although many different types of optical networks may be used depending on the particular application and network size, one common type of optical network is a Synchronous Optical Network (SONET).
In SONET networks, as well as other types of optical and non-optical networks, it is important to determine whether any errors exist in the communication of signals over the network. If such an error exists, then a network management system and/or network elements in the network may be notified so that the error may be addressed. For example, SONET networks may implement numerous types of protection switching techniques to address errors in the network, such as a node failure or a fiber cut. Furthermore, errors may be monitored to evaluate network compliance with agreements made between a network service provider and a network customer. For example, a network service provider may lease a particular amount of network capacity (for example, a particular number of network circuits) to a network customer and provide a service level agreement (SLA) to the customer guaranteeing the availability, performance, and/or any other appropriate metrics relating to the leased circuits. SONET networks and other types of networks implement techniques to monitor the performance of network circuits or other network connections to evaluate compliance with such SLAs.
However, although a customer may lease a number of circuits, the customer may not always use all of the leased circuits. For example, a customer may lease additional circuits for future use or for back-up use. Such circuits may not have customer premises equipment (CPE) connected to the circuit or such CPE may be inactive (meaning able to operate, but not sending any signals over the circuit). When an activated (for example, leased) circuit is not receiving any traffic from the CPE, SONET and other network elements typically generate alarm signals indicating the lack of an incoming signal. However, such alarm signals interfere with the monitoring of these circuits, and thus interfere with the evaluation of these circuits' compliance with an SLA and with other monitoring of the circuits.